In no way is browser compatibility on the Internet limited just to compliance with the latest web standards, since there is content on the World Wide Web that will not play nice with the latest iterations of Internet Explorer, Firefox, Opera, Chrome, etc.
Backwards compatibility is, in this regard, a critical aspect of having next-generation browsers not break the web. For Microsoft, not breaking the web with upcoming versions of IE has become one of the key goals of the development process, especially as, given IE’s dominance, many websites were built for the company’s proprietary browser.
“As IE changes and supports new technologies, developers will still want, in some scenarios, IE’s legacy behavior. There are many different technologies that enable developers to adjust how IE runs their site’s markup. The main ones include the IE Developer Tool’s Browser Mode and Document Mode, X-UA-Compatible Meta tag and HTTP Header, and Conditional Comments,”
Marc Silbey, IE program manager, revealed.
Setting the Browser Mode means that developers can control the User-Agent (UA) string IE sends to servers, but also the Document Mode the browser uses by default, and even how Conditional Comments are evaluated. Devs already familiar with IE8 know that the browser version uses IE8 standards as the default browser mode. The same will be valid for IE9, with Internet Explorer 9 being the default. The IE’s Developer Tools allow for this particular detail to be altered by changing the “Browser Mode:” menu item. At the same time, users can click on the Compatibility View button in order to achieve the same result.
According to Microsoft,
Internet Explorer 9 can use the following browser modes:
“- IE9 - IE9 reports a UA string, version vector, and document mode to match the default browser behavior, which is the most standards-compliant mode in IE9. Use this mode to test how IE9 users experience your site.